1. The problem statement, all variables and given/known data Find the coefficient of kinetic friction that is used to stop a train engine along its track of the trains velocity is 30 m/s when the brakes are applied, and it takes 30 sec for the 10,000 kg train to stop 2. Relevant equations Ffric=MN=Mmg (I think that's the equation to use. 3. The attempt at a solution Ffric=M(10000kg)(9.8m/s) Ffric=M(98,000) What do you use for the force? 30m/s?